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Summary of the impact

Research at the University of Bradford has enabled many major vehicle and
brake manufacturers
to improve the design of their brakes and braking systems to increase
customer satisfaction and
sales, and reduce costs. Methods have been developed to predict the
thermo-mechanical and
dynamic performance of brakes and provide design improvements. Durable
solutions have been
developed for noisy brakes, which have reduced warranty costs for
approximately ten international
collaborating companies including Bentley, where a squeal noise from the
front brakes of a new
vehicle had prevented it from being released for production. Our research
has been embedded
into short courses, which have trained over 250 engineers since 2008 and
is incorporated into
Jaguar Land Rover's (JLR) professional training.

Underpinning research

Research into brakes and braking systems at the University of Bradford by
a team led by Andrew
Day (Professor 1993-2013) and including John Fieldhouse (Honorary
Professor, 2012-2013), Dr
Khalid Hussain (Lecturer 1994-2005, Senior Lecturer 2005-present), Dr
David Bryant (2012-2013)
and Mr A Alasadi (KTP Associate 2010-2011), extends over more than 25
years and includes drum
brake design and manufacture (ROR Rockwell TCS 1997, MCB/VALX 2008), car
brake system
design and simulation (Honda 2003, Jaguar 2004), braking stability (1)
(Ford 2003, 2005, 2009),
drum and disc brake noise (2,3) (Hyundai 1996, Ford 2005, JLR 2010, 2013,
Mando 2012), drum
brake judder (4) (Hyundai 2006), disc brake judder (5,6) (Bentley 2013),
regenerative braking and
failure mode avoidance (TMETC KTP 2011). The Bradford group's research has
generated
advanced and unique knowledge and expertise in many aspects of brake
performance and vehicle
behaviour during braking. The understanding of contact and pressure
distributions between the
rotor and stator components of a brake has led to fundamental changes in
brake design including
more compliant friction materials for disc brake pads which provide more
uniform pressure
distributions, and has highlighted the importance of improved distribution
of actuation force applied
to the pad back plate. The use of Finite Element methods for
thermo-mechanical and modal
analyses has been correlated with experimental data, and has demonstrated
how predictive
techniques can be used to avoid operational problems at the design stage.
We have recently
published the first fully comprehensive non-linear simulation of brake
noise generation using multi-body dynamics software from current research with JLR (2). Much of this
research has been
actively promulgated through the annual `Braking of Road Vehicles' short
course for industry.

Warranty claims from brake noise and judder have become a major problem
for all road vehicle
manufacturers and research expertise in this area has recently been
strengthened in the Bradford
group. Companies including JLR, Bentley, Ford, Hyundai, TMD, BPW, BMW,
Meritor, Volvo,
Bosch, Toyota, and Mando have sponsored brake noise research since 1993.
Examples include
two CASE awards and continuing research collaboration with Bentley (5,6)
which has led to an
advanced understanding of brake judder and the effects of thermo-elastic
and thermo-plastic
behaviour. It has generated a revised approach to brake disc design that
includes aerodynamic
design of the disc vents to give overall even heating and cooling of the
disc and has demonstrated
elastic distortion during heavy braking for the first time. In addition it
has led to the suggestion of
disc stress relieving to avoid in-service stress relieving and subsequent
disc distortion. Advanced
whole body visual techniques (holographic interferometry) have been
developed to analyse the
vibration characteristics of brake systems, forming the basis of a
predictive tool (3). These enable
both in-plane and out-of-plane absolute displacements to be investigated.
The techniques were
extended to record time-related images of disc modes while braking, and
showed that the disc
continues to vibrate under the pad and is not suppressed by it. We
explained why certain
frequencies were more likely to occur by investigating the disc/pad
interface geometry and have
provided a predictive tool for industry. We measured the dynamic interface
pressure of the pad and
showed that the general centre of pressure varied during braking.
Correlated over car and
commercial vehicle brake systems, we showed that a 15-20mm leading contact
offset would
increase disc brake noise propensity and predicted this to be possible
with normal 03bc values and
existing brake designs (3).

Details of the impact

Modern automotive brakes have to provide consistently high performance
over a wide range of
operating conditions including high temperatures and high speeds. It is a
technologically
challenging area of automotive engineering, and vehicle and brake
manufacturers are continually
required to improve their designs. We have worked closely with many
companies (a,b,c,d,e) so
that our research into road vehicle brakes and braking systems has enabled
them to understand
better the underpinning scientific principles, and implement new knowledge
and methods. The
result for the industry is improved customer satisfaction and reduced
warranty costs, for example
by 50% for JLR since 2010 (a).

On-going promulgation of research knowledge and expertise in the field is
achieved via the annual
"Braking of Road Vehicles" short course run at Bradford since 1997.
Delegates attend this course
each year from all over the world, and it is internationally regarded as
the `industry-standard' short
course for the road vehicle and braking industries. It is also delivered
in-house to several
companies including JLR (a) where it is part of their Masters level
professional training programme.
Since 2008 we have trained over 250 engineers in advanced knowledge and
expertise (e.g. in
brake NVH) and have substantially improved the knowledge and understanding
of staff. For
example, in JLR's Brakes Engineering Department (a) this training is
already enabling new CAE
procedures to be developed e.g. in the minimisation of brake noise
propensity at the design stage
(2,a). Concerns relating to brake noise and vibration within JLR have
decreased as a result of
better understanding of brake noise among braking systems design engineers
which has resulted
in a saving of 471 days, and 3800 hours amongst the Brakes Engineering
Department staff (a). For
example, JLR took the decision to lower their in-house standard friction
level to 0.38, reducing
noise propensity because of the reduced leading contact offset (2).
Associated with other design
improvements, the result has been that since 2009 the number of identified
concerns relating to
brake noise and vibration has halved, warranty costs have been
substantially reduced, and
customer satisfaction has increased (a).

The advanced techniques of holographic interferometry developed by the
team have revealed
details of noisy brake systems that were previously unknown (3). Our
results have been
disseminated internationally and have been used to validate predictive
Finite Element (FE)
analysis procedures for brake design which have been adopted and used by
many brake and
vehicle manufacturers for noise prediction (a,b,c,d,e). Our predictive
tool for brake NVH is currently
being used by four vehicle and brake system manufacturers to support
understanding of how brake
noise is generated and to propose design improvements to avoid it.
Currently two UK car
manufacturers are using noise counter measures that were originally
proposed by the Bradford
team (Bentley and JLR). Prior to successful application of the
countermeasure, new Bentley
vehicles were unable to be released for production because of brake noise
(b).

We have worked closely with Bentley (5,6,b) over many years to advance
their understanding of
brake judder. This has resulted in their adopting stress relieving of
brake discs to ensure that
warranty claims arising from judder are minimised. The research is also
being used to direct
Bentley's future disc design and selection.

Sources to corroborate the impact

a. Manager, Brakes, Jaguar Land Rover,
"Jaguar Land Rover recognises and values highly the brake noise and
vibration expertise at
the University of Bradford ...".
"We recognise that members of the research group are internationally
recognised experts in
brake and braking system design ...".
"In the area of brake noise JLR has achieved high levels of customer
satisfaction and it is
essential that we continue to develop our scientific understanding and
knowledge to underpin
our technological expertise by working with universities such as
Bradford with specialist
expertise." (Letter dated 24/4/12.)

b. Functional Manager (Foundation Brakes), Bentley Motors Limited,"Bentley Motors has funded research projects with Professor Fieldhouse
since the 1990s ..."
"Bentley Motors currently expects to continue to collaborate with the
Centre in the research and
development of methods for improvements in brake NVH refinement."
(Letter dated 21/6/12.)

c. President and CEO, TMD Friction worldwide, TMD Friction Services GmbH"I am acutely aware of the challenges the automotive brake business
faces in the coming
years. Undoubtedly, we in the industry will face a whole gamut of
challenges - technical,
environmental and economic, over the next decade and strong research
capabilities in the UK
will be an essential support to ensuring the future of friction material
manufacture both in the
UK and the EU. TMD Friction would be happy to support you in
establishing the new Centre as
a key step towards this goal." (Letter dated 26/4/12.)

d. Chief Engineer, Meritor H.V.B.S. (UK) Ltd,"The new Braking Laboratory which is being established in the Research
Centre should include
"state of the art" equipment & facilities to make it one of the best
equipped braking research
laboratories in the world. I believe that this will provide braking
related R&D facilities which are
not currently available in the UK, and will help to develop stronger
links between academia &
industry which in turn will help develop a more competitive UK
manufacturing industry." (Letter
dated 24/4/12.)

e. Group Chief Engineer, Advanced Engineering, Tata Motors European
Technical Centre,"The partnership has directly contributed to the expanding capability
of TMETC by developing
key technological expertise in 2 areas, viz. braking systems and new
product introduction
within a Failure Mode Avoidance (FMA) framework. This has increased the
value of TMETC in
serving the strategic needs of its parent group TML through the delivery
of a design
methodology for regenerative braking for low carbon vehicles (FEV's and
HEV's) based on
analysis and prediction, which is presented within a new product
development process based
on the Bradford FMA framework." (KTP 007377 final report, July 2011.)